There are advantages and disadvantages to using both of these in manufacture.
Forging a head
Traditionally, iron clubheads were hand forged by pounding hot metal with a mallet, which by today's methods is an expensive and time-consuming process. Today's forged clubs are made by precision machines, using hydraulic presses, which are capable of generating up to 12 tonnes of pressure evenly and consistently. This is still an expensive way to make a golf clubhead, and so the cost is passed down the line and is ultimately reflected in the price to the consumer.
In a lot of cases, the benefits of a forged clubhead do not justify the cost. One advantage of forgings is a better feel, which is usually not too relevant to a high handicapper. The main advantage of a forged head is that it is easier to alter specifications due to the softer material it is made from. It is much easier to bend a forged clubhead for loft and lie than it is a cast head. Also, soft carbon steel will bend much further than a cast head. If a golfer needs a clubhead 4° or 5° upright they would be best advised to look at forged irons, despite the expense.
Cast in steel
Cast clubs are much less expensive to produce, and are less labour intensive, which in turn is reflected in the price to the end user. Clubheads are produced using what is called a ‘lost wax' process. This ensures consistency of specifications from clubhead to clubhead, unlike in the forging process. Using a lost wax casting process ensures there is never any wear and tear on the master so the heads are identical from the first casting, through thousands of heads and many years later.
When a forged die is put under immense pressure day after day, eventually the die will start to distort which affects head shape and specifications. Therefore the first thing golfers should do on receipt of new forged irons is check the specifications!
Metal detector
Every year, club manufacturers are using more and more materials with different properties to try and improve performance. Some really do have relevance but in a lot of cases it is purely about creating a great marketing story. Here is a simple guide to material properties:
- Yield Strength - The amount a metal can be bent before any deformation cannot be reversed.
- Tensile Strength - The amount a metal can be bent before actual breakage. Zinc alloy clubheads are good examples of heads that break fairly quickly.
- Material Density - The weight of the metal (gm/cc). Cobalt, for example, is a heavy material at 7.8, while titanium is very light at 4.5.
- Elongation - This is related to ‘tensile strength', and is a percentage of the change in the material's length when load is applied. The greater the elongation percentage, the tougher and more ductile a material is. Elongation is the most reliable indicator of how bendable a club is. For example, a carbon steel clubhead has an elongation of 30% while 17-4 stainless steel is only 15%.
When it comes to physically bending clubs there are two methods that can be used; either a constant, ever-increasing pressure on the bar, or a series of short bursts of pressure. The first allows more ‘feel' while the second is more effective with very stubborn clubheads. Another factor that affects the ‘bendability' of a club is its hosel length. Short hosels can be extremely difficult to move and often a special bending bar is required.
Lastly, sometimes it doesn't matter how much care you take or how much you know about the materials in the clubhead, a club can unexpectedly break. This is often caused by an off centre bore in the hosel resulting in a thick wall one side and a very thin wall on the other. Unfortunately, it is impossible to tell until the head has broken! My advice to all custom fitters is to have a large sign on your Loft & Lie machine saying, "All Clubs Altered at Owner's Risk!"
